JournalledResource


1   /**
2    * com.mckoi.store.JournalledResource  11 Jun 2003
3    *
4    * Mckoi SQL Database ( http://www.mckoi.com/database )
5    * Copyright (C) 2000, 2001, 2002  Diehl and Associates, Inc.
6    *
7    * This program is free software; you can redistribute it and/or
8    * modify it under the terms of the GNU General Public License
9    * Version 2 as published by the Free Software Foundation.
10   *
11   * This program is distributed in the hope that it will be useful,
12   * but WITHOUT ANY WARRANTY; without even the implied warranty of
13   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   * GNU General Public License Version 2 for more details.
15   *
16   * You should have received a copy of the GNU General Public License
17   * Version 2 along with this program; if not, write to the Free Software
18   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
19   *
20   * Change Log:
21   * 
22   * 
23   */
24  
25  package com.mckoi.store;
26  
27  import java.io.IOException  ;
28  
29  /**
30   * An interface that allows for the reading and writing of pages to/from a
31   * journalled.
32   *
33   * @author Tobias Downer
34   */
35  
36  interface JournalledResource {
37  
38    /**
39     * Returns the page size.
40     */
41    int getPageSize();
42  
43    /**
44     * Returns a unique id for this resource.
45     */
46    long getID();
47    
48    /**
49     * Reads a page of some previously specified size into the byte array.
50     */
51    void read(long page_number, byte[] buf, int off) throws IOException  ;
52  
53    /**
54     * Writes a page of some previously specified size to the top log.  This will
55     * add a single entry to the log and any 'read' operations after will contain
56     * the written data.
57     */
58    void write(long page_number, byte[] buf, int off, int len) throws IOException  ;
59  
60    /**
61     * Sets the new size of the resource.  This will add a single entry to the
62     * log.
63     */
64    void setSize(long size) throws IOException  ;
65    
66    /**
67     * Returns the current size of this resource.
68     */
69    long getSize() throws IOException  ;
70    
71    /**
72     * Opens the resource.
73     */
74    void open(boolean read_only) throws IOException  ;
75    
76    /**
77     * Closes the resource.  This will actually simply log that the resource has
78     * been closed.
79     */
80    void close() throws IOException  ;
81  
82    /**
83     * Deletes the resource.  This will actually simply log that the resource has
84     * been deleted.
85     */
86    void delete() throws IOException  ;
87  
88    /**
89     * Returns true if the resource currently exists.
90     */
91    boolean exists();
92    
93  }
94  
95
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